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[TowerTalk] Rotor Shims

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Subject: [TowerTalk] Rotor Shims
From: (K7LXC)
Date: Wed, 31 Dec 1997 10:39:03 EST
In a message dated 97-12-31 08:41:22 EST, writes:

> The 'Ol Contester (TM), W9LT, taught me a neat trick for working with Rohn
>  25 pointy top -- he leaves the rotor shelf and everything else finger tight
>  until the antenna, mast and all are at the top of the tower, and then
>  tightens things starting with the mast-to-boom clamp and working out.  That
>  way (presuming that your mast is the right diameter, or properly shimmed),
>  all of the dimensionally sloppy connections, like the plate to leg U-bolts,
>  are tightened only after the precise ones are tight.  There's plenty of
>  clearance inside the pointy top, as long as your mast isn't bent.  If it
>  is, as Jim says, "problemo."

Hi, Pete --

     Good one! This will equalize everything down the rotator/mast train by
making it 'self-leveling'. It should minimize any mis-aligned/bent rotator
plate problems. This'll work for bind in thrust bearing alignment too. You
might not be able to eliminate the bind but you can sure minimize it. 

     The AS25G accessory/rotator plate is not a precision piece of hardware.
As has been pointed out already, it's just a bent piece of steel. One thing
that may help is to use your bubble level on it when you're installing it.
Doing this instead of measuring or eyeballing its location may be an
advantage. But chances are you may still want to go through the above
excercise to get it mostly plumb.

     Another thing to do is to install the rotator pointing North (you know
which way IT is). That way, it may only bind as you get into other headings
and not the busy JA-EU quadrants. The stresses on the system will be minimized
as you may not use those other headings (VK, SA) as often. 

73,  Steve  K7LXC

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